Communication devices such as User Equipments (UE) are also known as e.g. wireless terminals, mobile terminals and/or mobile stations. Communication devices are enabled to communicate or operate wirelessly in a Heterogeneous wireless communication environment comprising multiple networks or Heterogeneous Networks (HetNet) with access nodes, such as a cellular communications network which comprising Second/Third Generation (2G/3G) network, 3G Long Term Evolution (LTE) network, Worldwide interoperability for Microwave Access (WiMAX) network, etc., a satellite positioning system which comprising e.g. Global Positioning System, GPS, Global Navigation Satellite System, GLONASS, and Galileo Position System and a wireless local network, such as a Wireless Local Area Network (WLAN).
Communication devices may further be referred to as mobile telephones, cellular telephones, smart phones, laptops, tablet computers or phablets with wireless capability, just to mention some further examples. The communication device in the present context may be, for example, portable, pocket-storable, hand-held, computer-comprised, or vehicle-mounted mobile devices, enabled to communicate voice and/or data via an access node with another entity, such as another communication device or a server in the wireless communication environment.
Nowadays, almost all communication devices are equipped with a wireless local network unit, such as a WLAN unit and/or a stand-alone GPS unit. The wireless local network unit provides a connection for a communication device through an access point to the Internet with high bandwidth and low cost. The stand-alone GPS unit provides position information for a communication device with high accuracy by communicating with a satellite.
At present, optimisation of a network is generally done by drive tests. In the drive tests, an equipment (test mobile) collects all required information, e.g. radio measurements and location information etc. while the equipment is being driven in a car on the roads. This information is used offline by the network to analyse the coverage in different locations and based on the analysis, operation parameters, power, antenna locations, antenna tilts, etc. are optimised. Recently the Minimization of Drive Tests, MDT is introduced in the third Generation Partnership Project (3GPP) standardization Release-10 to minimize the cost of the traditional drive tests. The MDT enables network operators to utilize users' equipment to collect radio measurements and associated location information, in order to assess network performance while reducing the Operation and Expenditure (OPEX) associated with the traditional drive tests. When an MDT is implemented in a communication device, an MDT procedure in the communication device will be activated by a network to perform measurements. The MDT procedure may be done periodically or triggered by an event, typically when a received radio signal quality of a serving cell in the network is worse than a pre-defined threshold. The measurement report may be sent back immediately to the network as part of a Radio Resource Management (RRM) procedure, or logged in the communication device's memory and reported to the network when requested by the network.
One crucial part of the MDT as comparing to a normal measurements report is the location information. Because network operators have to know where to add more base-stations or access nodes to optimize cells coverage and improve cell relations based on the MDT report. Since users of a communication devices don't want to have their stand-alone GPS unit always on for assisting network operators to evaluate the network performance, or the GPS unit may not work properly, e.g. in shadowed areas, the availability and accuracy of a location information associated with the measurements report can be problematic. However, the location information is the most valuable data in the MDT report for network operators to find problems such as coverage holes or erroneous cell relations etc. to improve their services.
US2013190009 discloses a method for location option control for MDT. The UE determines the best positioning procedure from a list of available location options. Each location option is associated with a priority. The prioritization may be based on signal strength and/or quality of a cell and WiFi signals. However, the method has very complicated structure, e.g. with many trees and branches for selecting location options, so it is not a solution with efficiency or accuracy.